860 Configuring DHCP Server SettingsFigure 31-1. Message Exchange Between DHCP Client and ServerThe DHCP server maintains one or more set of IP addresses the and otherconfiguration information available, by request, to DHCP clients. Each set ofinformation is known as an address pool.After a client leases an IP address from the DHCP server, the server adds anentry to its database. The entry is called a binding.What are DHCP Options?DHCP options are collections of data with type codes that indicate how theoptions should be used. Options can specify information that is required forthe DHCP protocol, IP stack configuration parameters for the client,information allowing the client to rendezvous with DHCP servers, and so on.When a client broadcasts a request for information, the request includes theoption codes that correspond to the information the client wants the DHCPserver to supply. The Web pages and CLI commands to configure DHCPserver settings include many predefined options for the information that ismost commonly requested by DHCP clients. For example, DHCP clientdiscover requests typically include options for the IP address (option 50),subnet mask (option 1), default gateway (option 3), and DNS server (option6). These options are predefined.For options that are not predefined, you can enter the option code and specifythe data type along with the data that the switch should include in DHCPoffers. RFC2132 specifies many of the DHCP options. Additional options aredescribed in later RFCs.`D H C PD IS C O VE R (broadcast)D HC P O FFER (unicast)D H C PR E Q U ES T (broadcast)D H C PA C K (unicast)DHCP Client DHCP Server(PowerConnect Switch)
